This present invention concerns a method and apparatus for determining the precise direction of propagation of a neutral particle beam
Various wire shadow methods and related devices have been heretofore proposed for sensing the energy of a neutral particle beam so as to accurately determine its direction of propagation By a wire shadow method is meant a method of sensing the shadow of reduced beam particle density downstream of an interposed shadow forming wire so as to determine the centroid of the shadow and thereby establish the direction of propagation of the beam. In one such method, the current passing through a detector wire positioned downstream of the shadow wire is measured; and in another, the intensity of the visible fluorescence emitted from a coating on a downstream detector wire is measured.
It has been observed, however, that the current produced through such a downstream detector wire is not linearly related to the intensity of the beam, as is desirable, because of multiple current producing interactions. It has been also found that the speed and resolution provided by the aforementioned fluorescent coating method are not sufficient for certain applications.